End grain wood flooring



March 1939. A. ELMENDORF END GRAIN WOOD FLOORING Filed NOV. 19, 1936Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE 3 Claims.

The present invention relates particularly to a floor or floor coveringof wood in which the wearing face contains end grain. The object of thepresent invention is to produce such a floor or floor covering whichshall be much thinner than conventional wood block floors, and which canbe laid in the form of flexible sheets.

A further object of the present invention is to produce a floor materialor floor covering of the block type, which not only can be laid asflexible sheets but which, when laid, has its blocks securely tied tothe underlying floor or subfloor so as to avoid the danger thatindividual blocks will become displaced, either laterally or upwardly orthat large floor sections will at any time bulge upwardly asoftenhappens in the case of conventional block floors.

In carrying out my invention I produce a layer of comparatively thinwood blocks arranged in contact with each other, said layer having inone broad face thereof a system of deep grooves following joints betweenthe blocks. These grooves are filled with a suitable yieldable orplastic binding material, such as asphalt. A thin, flexible backing isthen laid upon this face of the layer of wood, and is secured to eachblock by a suitable mechanical fastening. I prefer to employ as thefastenings so-called metal stitching, which comprises little staplesdriven through the backing and into the wood blocks. There is preferablyonly a single staple for each block, driven into the block at about themiddle of the face in contact with the backing. The material may beconstructed in sheets or panels of any desired size which permits themto be readily handled and shipped. In laying the material, it is bondedto the underlying subfloor or other foundation, conveniently by means ofsuch an adhesive, for example, as the paste commonly employed to holddown linoleum and the like. After the material has once been laid, it isheld and cannot lift up bodily. Neither can the individual blocks rise,because each is held down by its mechanical fastening. The asphalt inthe grooves serves also to keep the blocks in place, particularly underthe jarring influence of trucks or the like running over the same.Because of the yieldable character of the binder, each block may expandand contract freely, but it simply becomes larger and smaller withoutany shifting bodily in any direction. Therefore, there is at no time anybodily shifting in the lateral direction of the floor as a whole. Inother words, each block is anchored at a fixed point in the supportingfoundation or subfloor and expansion and contraction of the wood resultssimply in the closing and opening of the joints between blocks and notin any actual shifting of the blocks themselves.

The various features of novelty whereby my invention is characterizedwill hereinafter be pointed out with particularity in the claims; but,for a full understanding of my invention and of its objects andadvantages, reference may be had to the following detailed descriptiontaken in connection with the accompanying drawing, wherein:

Figure l is a top plan view of a fragment of a panel or sheet offlooring embodying the present invention; Fig. 2 is a bottom view of thematerial illustrated in Fig. l, a portion of the flexible backing beingbroken away; Fig. 3 is an edge view of the panel illustrated in Fig. 1;Figs. 4 and 5 are sections taken respectively on lines d-d and 5-5 ofFig. 1; and Figs. 6 and '7 are respectively a side view and a bottomview of a block having a somewhat different form than that in theprevious figures.

Referring to Figs. 1 to 5 of the drawing, l represents a comparativelythin flexible backing sheet, such as reasonably thick tough paper orfelt saturated to make it waterproof. Overlying this backing layer aretiles or blocks of Wood 2, of any desired size and shape, arranged sideby side in engagement with each other. These blocks are preferablyarranged with the grain of the wood therein running from top to bottom,so that the upper or wearing face of the assembly contains end grain.However, for some purposes certain features of the invention mayadvantageously be employed where the grain of the wood does not run moreor less at right angles to the plane of the sheet or slab. My improvedflooring, composed of blocks about an inch high and having end grain intheir wearing faces, has given very satisfactory results. Such blocksmay, if desired, be as wide and as long as they are high, this beingabout the shape which I have illustrated by Way of example,

The lower ends of the blocks are of reduced size so that when a group ofblocks are placed together and form rows transverse to each other, thereappears in the bottom face of the assembly a network of grooves whichcoincide with the joints between the blocks in the assembly. The firststep in producing a thick composite sheet or slab is to set therequisite number of blocks upside down in a suitable form, after whichthe grooves are filled with a suitable binding material which remainsplastic under continued stresses. Asphalt may advantageously be employedas the binder. The binding material may simply be poured or dumped onthe assembled blocks and be scraped or otherwise worked over the face ofthe assembly until the grooves have become packed, and the excessbinding material may then be scraped off. It is to a large extent amatter of choice whether the binding material be confined entirely tothe grooves or whether a layer of greater or lesser thickness be alsopermitted to overlie the block assembly. If all of the excess bindingmaterial is scraped off, the face of the block assembly shows a networkof strands or narrow bands of binding material, as indicated at 3 inFig. 2.

After the binding material has been applied, the fiexible backing sheetI is laid on the assembly and is mechanically fastened to eachindividual block. I prefer to employ only a single fastening for eachblock, placed at about the center of the latter. These mechanicalfastenings may conveniently be little metal staples 4 which can bequickly and accurately driven by a suitable socalled stitching machine.

The material is now ready for use. In laying it upon a subfloor, theside having thereon the backing sheet is placed next to the subfloor, asshown in Fig. 3, where the subfloor is indicated at 5. Each sheet orslab as it is laid upon the subfloor is bonded to the latter by asuitable adhesive, conveniently of the kind employed in securinglinoleums to a floor.

After the binding material between the flooring sheets or slabs and thesubfloor has set, each block is anchored firmly to the subfloor andconsequently, even if the blocks become wet to a degree that causesordinary fioors composed of blocks set into asphalt to bulge upward,they remain down against the subfloor and the wearing surface of thefloor proper remains fiat. Each block can expand and contract indirections parallel with the floor, independently of every other block,but cannot move bodily in a lateral direction any more than it can moveupwardly. For this reason no bodily shifting of the floor in a lateraldirection can occur.

If the wood contains from ten percent to twelve percent moisture at thetime the flooring is laid, it is not likely thereafter to have a highermoisture content, assuming it to be a floor within a building.Therefore, starting with this moisture content, if the blocks dry outsomewhat, they contract and the joints in the upper face of the flooropen slightly; but, since the center of each block is held in a fixedposition, there can be no cumulative effect in the opening of the jointsthat might cause wide cracks to appear in some parts of the floor. Then,upon again taking up moisture, the blocks simply expand and close up thejoints.

The network of asphalt or the like does not prevent the expansion andcontraction of the blocks, since it is sufiiciently plastic to yieldsatisfactorily to the slow movements of the meeting faces of adjacentblocks from and toward each other during contraction and expansion ofthe wood. The individual strands or elements of the network of asphaltshould have sufiicient cross sectional area and sufficient verticaldepth to insure that the bonds between the same and the locks will notbe destroyed and that the strands will not be torn apart and allow waterto flow downwardly through them, and to cause the binding material tohold each block down firmly enough to make it difficult for any block totilt under forces to which it may be subjected due to the passing of thewheel of a truck or the like over the same. Were it not for this networkof binding material, there would always exist the danger of tearing someof the blocks loose from the backing under lateral thrusts thereoncaused by a heavily loaded truck passing over the same. Good resultshave been obtained by making the grooves of a flooring in which theblocks are not over one inch thick about a quarter of an inch deep. Thegrooves may be of any desired widths, and their cross-sectional shapesmay vary. In Figs. 1 to 5, the grooves are rectangular in cross section,this result being obtained by cutting away the wood to a depth ofsomewhat less than an eighth of an inch from each side of each block fora distance of about one-quarter of an inch from the bottom face of theblock. If it be desired that the grooves be triangular in cross section,blocks such as indicated at 6 in Figs. 6 and 7 may be chamfered alongall sides, at the bottom, as indicated at 1.

While any desired bonding material may be placed between the flexiblebacking and the subfloor, the present invention, for the first time,makes it possible to employ an adhesive which sets in a non-plasticstate. In the case of a flooring in which the blocks may shift bodily,so that a whole fioor or a large section thereof tends to move laterallyas a unit, the bond between the backing and the subfloor would crack andpermit the backing to tear loose, if the bonding material were of thetype commonly used for fastening down linoleum, such bonding materialbecoming hard as it sets. Obviously, a much stronger bond results froman adhesive which soon becomes non-plastic than from a bonding materialthat remains plastic as does asphalt and, therefore, I am able to fastendown my flooring much more effectively than has heretofore been possiblein the case. of more or less similar wood floorings.

While I have illustrated and described with particularity only a singlepreferred form of my invention, I do not desire to be limited to theexact structural details thus illustrated and described; but intend tocover all forms and arrangements which come within the definitions of myinvention constituting the appended claims.

I claim:

1. A preformed floor covering comprising a o flexible backing sheet andan overlying layer of wood blocks or tiles resting loosely on the same,said blocks being in contact with each other and having in their lowerfaces deep grooves following the joints between the same, a plasticbinding material filling said grooves, and fastening means extendingthrough said backing sheet into each block, the fastening means for eachblock being localized in an area which is only a small fraction of thearea of the block, whereby each block is anchored while left free toexpand and contract independently of the backing sheet under changes inmoisture content.

2. A preformed floor covering comprising a flexible backing sheet and anoverlying layer of wood blocks or tiles resting loosely on the same,said blocks being in contact with each other and having in their lowerfaces deep grooves following the joints between the same, a plasticbinding material filling said grooves, and a single staple extendingthrough said backing sheet into each block.

3. A preformed floor covering comprising a flexible backing sheet and anoverlying layer of wood blocks or tiles resting loosely on the. same,

means for each block being localized in an area which is only a smallfraction of the area of the block, whereby each block is anchored whileleft free to expand and contract independently of the backing sheetunder changes in moisture content. 5

ARMIN ELMENDORF.

